1. Field of the Invention
This invention relates generally to ignition systems for internal combustion engines and more specifically, to an improved electronic ignition for supplying high voltage pulses to spark plugs for engines used in automobiles, motorcycles, boats, airplanes, and the like.
2. Prior Art
Ignition systems for firing spark plugs in automobile engines and the like comprises an old art dating back to the early part of the 20th century and a great many patents have been issued in that art. Conventional ignition systems comprising a battery, an ignition coil, a condenser (capacitor), breaker points and a distributor, have been used virtually universally for decades but have produced a number of disadvantages related to durability and performance and the effect on the frequency of engine tune-up requirements. Accordingly, in about the mid 1960's with the advent of advances in solid state electronics, transistorized electronic ignition systems became available. Since that time, a number of improvements have been made and today virtually all automobile manufacturers provide either inductive-discharge ignition systems or capacitive-discharge ignition systems in their products. The inductive-discharge ignition system uses a transistor to cut-off the current flowing in the primary winding of the ignition coil instead or using breaker points of the conventional system. Typical capacitive-discharge ignition systems use a silicon controlled rectifier (SCR) to discharge a previously charged capacitor through the primary winding. Detailed examples of electronic ignition systems of the prior art and their relative advantages over the aforementioned conventional ignition systems are provided in a book entitled "Electronic Ignition Systems" by Marvin Tepper, published by the Hayden Book Company, Copyright 1977. Such prior art electronic ignitions find their principal advantage relative to the previous non-electronic ignitions in alleviating the short term problems. Such problems were previously encountered primarily with breaker points which required frequent replacement due to high current induced rapid wear. Electronic ignitions make it possible to replace such breaker points with a different form of triggering device for the first time made compatible with internal combustion engines.
Unfortunately, many of the problems previously associated with conventional ignition systems are not solved by the electronic ignition systems of the prior art. For example, prior art electronic ignition systems still suffer the disadvantage of a decreasing high voltage output at the spark plug particularly as engine speed increases. Furthermore, spark duration is still relatively short at between 0.5 and 2 microseconds, thus severely limiting the amount of energy that is delivered by the spark plug within the explosive chamber. Furthermore, the number of spark plug ignitions that induce the combustion process is too low and as a result, the combustion effect is not as efficient as it should be and spark plugs become fouled, causing misfirings and frequent cleaning, replacement or tuneups are often needed.